A lithium air battery is an electrochemical energy conversion device which includes a lithium negative electrode, a lithium ion conductive electrolyte, and an air electrode in which reversible electrochemical reaction of oxygen and lithium ions may occur. Generally, the lithium air battery has theoretical energy density of 11,000 Wh/kg to provide high energy density as compared with a conventional lithium ion battery. Further, as compared with the conventional lithium ion battery, the lithium air battery is not expensive, is eco-friendly, and has excellent stability, and as a result, active research and development of the lithium air battery has been conducted as a power source for electric vehicles.
However, in order to commercialize such a lithium air battery, there are still many things to be improved. For example, rate of decomposition reaction during charging may be reduced by solid products such as Li2O2 which may be generated in the air electrode during discharging of the lithium air battery. Further, the solid products may not be dissolved in the liquid electrolyte to block pores of the air electrode, and as a result, charge/discharge efficiency may be reduced. Further, since the lithium air battery is driven in an open system unlike conventional lithium secondary battery, the used liquid electrolyte may be evaporated and deterioration of battery performance may occur.
In addition, the conventional lithium air battery has a problem that the battery performance may be rapidly reduced as the liquid electrolyte is easily evaporated during the charging and discharging processes, or loss due to leakage may be generated. Further, because a liquid electrolyte with high reactivity is used, there is a problem in that lithium dendrite may be formed on the lithium negative electrode during charging and discharging to deteriorate charge/discharge efficiency and a lifespan.
Accordingly, the research and development for solving problems including volatilization of the electrolyte and the growth of dendrite which are generated in the lithium air battery, oxidative decomposition of the polymer due to active oxygen radicals generated in the air electrode, and the like has been urgently required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.